Exploratory analysis of local extreme-temperature attributable mortality in an urban city of Madrid

AIM

to assess the Heat (HW) and Cold Waves (CW) risks on health in the urban municipality of Getafe.

METHODOLOGY

time series analysis between 01/01/1999-31/10/2013.

DEPENDENT VARIABLE

daily mortality due to natural causes - (ICD-10): A99-R99-.

INDEPENDENT VARIABLES

the maximum (Tmax) and minimum (Tmin) daily temperature. The mortality-temperature relationship was analysed to determine the thresholds of HW (Thresholdheat) and CW (Thresholdcold). Using Poisson GLM (link = log), the Relative Risk (RR), Attributable Risk (AR) and Attributable Mortality (AM) were determined for each degree of the Tmax exceeding the Thresholdheat (Theat) and for each degree of Tmin under the Thresholdcold (Tcold). Finally, socioeconomic variables were analysed descriptively.

RESULTS

Thresholdheat was 36 °C while Thresholdcold was 0 °C. The RRs associated with Theat, i.e. 1.08 (1.03 1.14), are akin to those obtained for Tcold, i.e. 1.05 (1.03 1.08). There were 202 HW and 430 CW episodes. The AM to HW totalled 61 (25, 96) deaths, while that attributable to CW reached 146 (82,211) deaths. The vulnerability in Getafe seems to be lower than in surrounding similar urban and rural cities.

CONCLUSIONS

The singular urban development of the municipality may have granted it an advantage over surrounding municipalities regarding temperature extremes.

Gender differences in adaptation to heat in Spain (1983-2018)

In Spain the average temperature has increased by 1.7 °C since pre-industrial times. There has been an increase in heat waves both in terms of frequency and intensity, with a clear impact in terms of population health. The effect of heat waves on daily mortality presents important territorial differences. Gender also affects these impacts, as a determinant that conditions social inequalities in health. There is evidence that women may be more susceptible to extreme heat than men, although there are relatively few studies that analyze differences in the vulnerability and adaptation to heat by sex. This could be related to physiological causes. On the other hand, one of the indicators used to measure vulnerability to heat in a population and its adaptation is the minimum mortality temperature (MMT) and its temporal evolution. The aim of this study was to analyze the values of MMT in men and women and its temporal evolution during the 1983-2018 period in Spain's provinces. An ecological, longitudinal retrospective study was carried out of time series data, based on maximum daily temperature and daily mortality data corresponding to the study period. Using cubic and quadratic fits between daily mortality rates and the temperature, the minimum values of these functions were determined, which allowed for determining MMT values. Furthermore, we used an improved methodology that provided for the estimation of missing MMT values when polynomial fits were inexistent. This analysis was carried out for each year. Later, based on the annual values of MMT, a linear fit was carried out to determine the rate of evolution of MMT for men and for women at the province level. Average MMT for all of Spain's provinces was 29.4 °C in the case of men and 28.7 °C in the case of women. The MMT for men was greater than that of women in 86 percent of the total provinces analyzed, which indicates greater vulnerability among women. In terms of the rate of variation in MMT during the period analyzed, that of men was 0.39 °C/decade, compared to 0.53 °C/decade for women, indicating greater adaptation to heat among women, compared to men. The differences found between men and women were statistically significant. At the province level, the results show great heterogeneity. Studies carried out at the local level are needed to provide knowledge about those factors that can explain these differences at the province level, and to allow for incorporating a gender perspective in the implementation of measures for adaptation to high temperatures.

Temporal evolution of threshold temperatures for extremely cold days in Spain

In contrast to research on heat waves, there are no studies in recent years that analyze the temporal evolution of threshold temperatures (Tthreshold) for extremely cold days (ECD). It is unknown whether threshold temperatures have increased more quickly than the minimum daily temperature (Tmin) in recent years. The objective of this study was to analyze the temporal evolution of the minimum daily temperature (Tmin) in a group of Spanish provinces and compare it with the evolution of threshold temperatures. An ecological, retrospective time series study was carried out using daily observations between January 1, 1983 and December 31, 2018 (36 years) in 10 provinces that are representative of the different climate territories in Spain. For each representative observatory in each province, the values of Tmin were obtained for the winter months (November-March). The value of Tthreshold was determined for each province and each year, using dispersion diagrams for the pre-whitened series, with daily mortality due to natural causes displayed on the Y axis (CIEX: A00-R99) and Tmin grouped by 10 degree intervals on the X axis. To determine the temporal evolution of Tmin and Tthreshold for each province, linear models were fitted, with time as the independent variable. During the winter months, Tmin increased at an average rate of 0.2 °C/decade (IC95: 0.1-0.3), while Tthreshold remained practically constant during the period, at 0.1 °C/decade (IC95% -0.1 0.3). These values are much lower than those obtained in the case of heat, both in terms of the evolution of maximum daily temperature and that of Tthreshold. In conclusion, the fact that this trend has been maintained across time in a scenario of climate change, with a slow increase in minimum daily temperatures and constant values of Threshold, suggests a decrease in the number of ECD.

Evolution of the minimum mortality temperature (1983-2018): Is Spain adapting to heat?

The objective of this study was to analyze at the level of Spain's 52 provinces province level the temporal evolution of minimum mortality temperatures (MMT) from 1983 to 2018, in order to determine whether the increase in MMT would be sufficient to compensate for the increase in environmental temperatures in Spain for the period. It also aimed to analyze whether the rate of evolution of MMT would be sufficient, were it to remain constant, to compensate for the predicted increase in temperatures in an unfavorable (RCP 8.5) emissions scenario for the time horizon 2051-2100. The independent variable was made up of maximum daily temperature data (Tmax) for the summer months in the reference observatories of each province for the 1983-2018 period. The dependent variable was daily mortality rate due to natural causes (ICD 10: A00-R99). For each year and province, MMT was determined using a quadratic or cubic fit (p < 0.05). Based on the annual MMT values, a linear fit was carried out that allowed for determining the time evolution of MMT. These values were compared with the evolution of Tmax registered in each observatory during the 1983-2018 analyzed period and with the predicted values of Tmax obtained for an RCP8.5 scenario for the period 2051-2100. The rate of global variance in Tmax in the summer months in Spain during the 1983-2018 period was 0.41 °C/decade, while MMT across the whole country increased at a rate of 0.64 °C/decade. Variations in the provinces were heterogeneous. For the 2051-2100 time horizon, there was predicted increase in Tmax values of 0.66 °C/decade, with marked geographical differences. Although at the global level it is possible to speak of adaptation, the heterogeneities among the provinces suggest that the local level measures are needed in order to facilitate adaptation in those areas where it is not occurring.

Evolution of the minimum mortality temperature (1983-2018): Is Spain adapting to heat?

The objective of this study was to analyze at the level of Spain's 52 provinces province level the temporal evolution of minimum mortality temperatures (MMT) from 1983 to 2018, in order to determine whether the increase in MMT would be sufficient to compensate for the increase in environmental temperatures in Spain for the period. It also aimed to analyze whether the rate of evolution of MMT would be sufficient, were it to remain constant, to compensate for the predicted increase in temperatures in an unfavorable (RCP 8.5) emissions scenario for the time horizon 2051-2100. The independent variable was made up of maximum daily temperature data (Tmax) for the summer months in the reference observatories of each province for the 1983-2018 period. The dependent variable was daily mortality rate due to natural causes (ICD 10: A00-R99). For each year and province, MMT was determined using a quadratic or cubic fit (p < 0.05). Based on the annual MMT values, a linear fit was carried out that allowed for determining the time evolution of MMT. These values were compared with the evolution of Tmax registered in each observatory during the 1983-2018 analyzed period and with the predicted values of Tmax obtained for an RCP8.5 scenario for the period 2051-2100. The rate of global variance in Tmax in the summer months in Spain during the 1983-2018 period was 0.41 °C/decade, while MMT across the whole country increased at a rate of 0.64 °C/decade. Variations in the provinces were heterogeneous. For the 2051-2100 time horizon, there was predicted increase in Tmax values of 0.66 °C/decade, with marked geographical differences. Although at the global level it is possible to speak of adaptation, the heterogeneities among the provinces suggest that the local level measures are needed in order to facilitate adaptation in those areas where it is not occurring.

The evolution of minimum mortality temperatures as an indicator of heat adaptation: The cases of Madrid and Seville (Spain)

The increase in the frequency and intensity of heat waves is one of the most unquestionable effects of climate change. Therefore, the progressive increase in maximum temperatures will have a clear incidence on the increase in mortality, especially in countries that are vulnerable due to geographical location or their socioeconomic characteristics. Different research studies show that the mortality attributable to heat is decreasing globally, and research is centred on future scenarios. One way of detecting the existence of a lesser impact of heat is through the increase in the so-called temperature of minimum mortality (TMM). The objective of this study is to determine the temporal evolution of TMM in two Spanish provinces (Seville and Madrid) during the 1983-2018 period and to evaluate whether the rate of adaptation to heat is appropriate. We used the gross rate of daily mortality due to natural causes (CIEX: A00-R99) and the maximum daily temperature (°C) to determine the quinquennial TMM using dispersion diagrams and realizing fit using quadratic and cubic curvilinear estimation. The same analysis was carried out at the annual level, by fitting an equation to the line of TMM for each province, whose slope, if significant (p < 0.05) represents the annual rate of variation in TMM. The results observed in this quinquennial analysis showed that the TMM is higher in Seville than in Madrid and that it is higher among men than women in the two provinces. Furthermore, there was an increase in TMM in all of the quinquennium and a clear decrease in the final period. At the annual level, the linear fit was significant for Madrid for the whole population and corresponds to an increase in the TMM of 0.58 °C per decade. For Seville the linear fits were significant and the slopes of the fitted lines was 1.1 °C/decade. Both Madrid and Seville are adapting to the increase in temperatures observed over the past 36 years, and women are the group that is more susceptible to heat, compared to men. The implementation of improvements and evaluation of prevention plans to address the impact of heat waves should continue in order to ensure adequate adaptation in the future.

Short-term effects of Saharan dust intrusions and biomass combustion on birth outcomes in Spain

The objective of this study is to analyze the short-term effects of atmospheric pollutant concentrations (PM₁₀, NO₂ and O₃) and heat and cold waves on the number of pre-term births and cases of low birth weight related to Saharan dust advection and biomass combustion. The dependent variables used in this analysis were the total number of births, births with low weight (>2.500 g) and pre-term births (<37 weeks), that occurred at the province level. Data provided by the NSI included: days with Saharan dust intrusion or biomass advection classified in terms of information provided by MITECO for each of the nine regions in Spain. A representative city was selected for reach region in which the registered average daily concentrations of PM₁₀, NO₂ and O₃ (μg/m³) were used. These were also provided by MITECO. The daily maximum and daily minimum temperature (°C) used was those registered by the meteorological observatory station located in each province capital, provided by AEMET. Using Poisson log linear regression models, the associated relative risks (RR) were measured as well as the population attributable risk (PAR) corresponding to the variables that resulted statistically significant at p < 0.05 for days with and without intrusion of natural particulate matter. The results obtained show that the days with Saharan dust intrusion or advections due to biomass combustion- beyond the impact of PM₁₀, primary pollutants such as NO₂ (in Saharan intrusions), heat waves and O₃ - are associated with the number of births, low birth weight and pre-term birth. The RR and percent PAR of the pollutants and the heat waves are greater than those obtained for PM₁₀. The results of this study indicate that days with natural particulate matter due to biomass combustion or advection of Saharan dust put pregnant women at risk.